4K – The big picture…

It seems like only yesterday that we were contemplating the introduction of HD (High Definition) television and its potential impact on the broadcast industry… Then along came tapeless workflows, closely followed by a flurry of excitement over 3D television… Now 4K appears to be the latest trend for broadcast technology – So should we be getting excited about 4K and preparing to adopt it, or will it be a short-lived ‘fad’ that we’d be better off ignoring?

As with most of the broadcast technologies that have been introduced over the last five years, before diving head first into 4K you should perhaps stop, take a breath and calmly observe what’s happening in the world of consumer technology first, because if there isn’t an established (or rapidly crystallising) market for your new content then it will be difficult to make additional revenue from it…

Where is the demand for 4K content coming from OR likely to come from?

Packaged Media (eg Blu-Ray disc movies / games content)

Potentially (Sony PS4??)

Digital Download to mobile devices

No

Cable, Satellite or Terrestrial Broadcasting

Not planned at all yet

Digital Cinema

YES

Specialist Applications, eg. crowd surveillance

Likely

So even this brief appraisal of the potential markets clearly illustrates that Digital Cinema (and other former applications for 35mm film production such as commercials & high end television dramas) is the key commercial application for 4K production today.

What about 4K television? If we bear in mind that it’s getting on for 40 years since the pioneering days of HDTV in the mid 1970’s, it is perhaps surprising that even today not all content is produced in HD and even if it were, not everyone can view HD in their home because the roll-out of HD television remains far from complete – I’d therefore expect that whilst there will be an inexorable move towards the adoption of 4K it’s going to be quite a while before we’re sitting down to eat our TV dinners watching Coronation Street or Eastenders in glorious 4K!

But every boy scout knows it pays to be well prepared, so let’s get our heads around this whole 4K thing now!

What is 4K?

In the world of Digital Cinema it’s very clearly laid out by the DCI (Digital Cinema Initiative) that the pixel count specification for 4K projection is 4096 x 2160 (8.8M pixels). Therefore, in order to attain the best possible 4K image quality this resolution should be preserved pixel for pixel throughout the entire production and post-production process.

Of course that would be far too easy! So to add a bit of confusion, in addition to DCI standard 4K, at the consumer or professional area of the market 4K is regarded as 3840 x 2160 (8.3M pixels), a resolution that conveniently equates to four times the gross pixel count of Full HD. This resolution is referred to as QFHD (Quad Full High Definition, or Quad HD).

Sony’s F65 and Red Digital Cinema’s Epic are DCI compliant large sensor 4K cameras, targeting the high-end Digital Cinematography market with absolute focus on camera performance and image quality, whereas JVC’s new GY-HMQ10 is a low cost compact QFHD camcorder with 1/2″ CMOS sensor that’s aimed unashamedly at the higher volume ‘pro-sumer’ end of the market where users want the maximum ‘bang (or resolution) for their buck’ even if ultimate quality is compromised to keep the price down! JVC hopes that their GY-HMQ10 will make significant penetration into an emerging market for 4K amongst resolution-hungry non broadcast producers (i.e. corporate, industrial and educational).

4K on a shoestring…

You may be wondering if the GY-HMQ10 will lend itself to ultra-low budget digital cinema production, or perhaps be used as a “B-Roll” or “crash” camera in mainstream motion picture production? Whilst there’ll doubtless always be someone out there hell-bent on doing so I’d suggest the sensible answer is no, because whilst the output quality is great for an inexpensive 4K video camera, with a comparatively small 1/2″ sensor it is just that rather than an uncompromising large sensor digital cinematography camcorder like the F65!The GY-HMQ10 is not restricted to 4K shooting – It can shoot full HD 1920 x 1080, or it can output Full HD from a 4K clip in real-time, giving you the ability to down-convert or pan & scan a full HD window within the original 4K image… This technology has immense potential – Imagine filming sports events and then having the ability to zoom in and pan across the picture in real-time in full HD! These benefits can be applied to many applications – For example a Police force could record events or protests with the ability to zoom, pan and scan and clearly identify anyone in shot after the event. For medical applications surgical procedures can now be captured in unprecedented detail for training and analysis purposes. The possibilities are almost endless.

In order to keep the camera and recording media costs down whilst making the GY-HMQ10 as easy to use as possible JVC have cleverly used existing consumer technology – The GY-HMQ10 has a 4K 1/2″ CMOS sensor up-front but rather than recording a single data file it divides the 4K image into four full HD images and thereafter simultaneously records each quadrant onto a separate SDHC card using efficient MPEG-4/H.264 compression. The data rate is 144Mb/s, equating to a very respectable 36Mb/s per full HD quadrant, so the recorded quality is excellent. The only complication is that rather than one SDHC card to back-up (or lose) you now have four cards and in order to reconstruct your 4K video you have to use JVC’s proprietary software to synchronise and stitch the material together. For this task and viewing purposes you’ll need a highly specified Windows PC or Apple computer equipped with a Quad DVI-D graphics card. Don’t forget that if you want to view your pictures in one piece at full resolution you’ll need a QFHD consumer television or display too!

Let’s turn our attention to the F65 to identify why these two products are poles apart – Even if we disregard their huge price differential!

4K for Digital Cinema

In the realms of Cinema the aesthetic ‘look’ and ‘feel’ of the image is of paramount importance. This is largely because the incumbent technology and quality threshold has already been defined by 35mm film and embraced by cinema audiences over many decades. In order to match the quality of 35mm film, Sony has seemingly raided its technology war-chest to accelerate the development of a camera that not only delivers 35mm performance, but exceeds it – a feat which they hope will firmly establish them as the leading force in Digital Cinematography acquisition. The Sony F65 conforms to the strict DCI specification of pixel for pixel 4096 x 2160 resolution by utilising a “zig-zag” sampling technology from its bayer pattern sensor, ensuring that 4K is actually 4K. But resolution is not the only key driver – latitude, sensitivity and colour gamut also play vital roles. Latitude is always a key issue for cinematographers but with 14-stops to play with the F65 is more than up to the task – Dial in the sensor’s native sensitivity of ISO 800 combined with incredibly low noise levels and it’s a brave D.O.P who would not want to shoot with the F65!

When it comes to quality, colour gamut is another important factor which if not managed correctly can lead to a differential between what the D.O.P. thinks he (or she) has captured on set versus what is eventually projected in the cinema… So why is that? In simple terms, we currently live in a world of HD broadcast where we are used to working in either an 8 or 10-bit colour depth with 4:2:2 colour sampling within a narrow colour gamut known as Rec709 (the Rec709 is a standard derived from the colour space that can be displayed on a typical HDTV monitor and many cameras are capable of acquiring a far wider colour gamut) . As the Rec709 colour gamut can be loaded in to the camera and maintained throughout the workflow what we tend to see on-screen at home is very close to what was actually acquired in the camera.

In order to deliver the most life-like colours combined with the maximum possible latitude for subsequent post-production the F65 ‘sees’ and can capture a far wider colour gamut than Rec709. In fact, thanks in part to its 16-bit linear RAW recording system the F65 reproduces a range of colours that far exceeds not only the current DCI P3 standard for digital cinema projection but also the SMPTE specification for colour negative film!

At the moment there isn’t a universally accepted colour gamut standard that can cope with the F65’s full colour space potential but this may not be for long because US based AMPAS (the Academy of Motion Picture Arts & Sciences technology committee) have proposed the adoption of their IIF/ACES system (Image Interchange Format / Academy Color Encoding Specification) in order to help avoid the instance of colour gamut errors whilst also allowing the use of a far wider colour gamut than Rec.709 or even 35mm film (The IIF/ACES system provides for a theoretically unlimited range of visible colours).

In addition, the introduction of LUTs (Look-Up Tables) and CDLs (Colour Decision Lists) allows the preservation of the camera’s complete colour gamut throughout the entire post production process, thus preserving the ability to apply a range of display-specific colour gamuts to the content prior to distribution. Just think of LUTs and CDLs as advanced metadata for colours: It’s a far better process than working with material that has been irreversibly modified by the application of in-camera gamma curves.

So when it comes to Latitude, Sensitivity and Colour Gamut the F65 delivers more. Where more can be a distinct disadvantage is the matter of file sizes and the subsequent cost of the larger recording media required for their storage. When shooting 4K at 24p and capturing in 16-bit F65RAW format the F65 generates 15GB of data per minute – That’s a staggering 43x more than an XDCAM EX camera shooting full HD at 35Mb/s! To cope with this the F65 uses special solid-state ‘SR Memory’ media cards which are available in 256GB, 512GB and 1TB capacities. These will sustain a guaranteed read and write data rate of up to 5.5Gb/s! It’s worth pointing out that the task of dealing with files of this magnitude has created the new role of “Data Wrangler” or DIT (Digital Imaging Technician). This person’s responsibilities include the provision of on-set data handling services such as file back-up, archiving, validation, LUT management and digital dailies…

Workflow is equally as challenging, larger files ensure that a traditional off-line and on-line workflow with a final picture grade is a given. The resultant additional quality in terms of resolution, colour and dynamic range contained within the data files will be ‘the icing on the cake’ and make all of the extra effort worthwhile.

In terms of the the final deliverables, it’s likely that you will be asked to create a DCI compliant JPEG 2000/MXF file for 4K or even 2K Digital Cinema projection as well as a Sony HDCAM SR master tape for broadcast and commercial use.

It’s clear that with high-end 4K a well honed and thoroughly rehearsed workflow is absolutely essential – Without one you could be burning cash like it’s going out of fashion!

A typical F65 RAW workflow:

So that’s an insight into the top and bottom end of 4K cameras but you may be wondering what sits in-between? At the moment the answer is simple: Nothing! This is doubtless because at the moment we are barely able to deliver HD pictures to the home via the traditional route of terrestrial television so QFHD, let alone 4K. Even with the latest compression technologies 4K broadcasting is simply not viable.

Could we expect to see a mid-range 4K camcorder from Sony, Canon or Panasonic in the not too distant future? Sure, but it’ll have to be fully backward compatible with today’s HD standards if any sane person will invest before mainstream 4K broadcasting is adopted. Until then 4K adoption is likely to be confined to two market segments: The motion picture industry at the high-end and then corporate, medical, industrial, security and educational users in the entry-level Quad HD sector.

In Summary:

The 4K revolution has begun, with advanced cameras like the F65 completely eliminating the need for traditional film as the big Hollywood studios switch to digital acquisition and file based delivery. To this end it’s very encouraging to see that the DCI (a joint venture between Disney, Fox, Paramount, Sony Pictures, Universal and Warner Bros.) are pushing hard for 4K to become the new industry standard.

Will 4K break in to the domestic market? That is only a matter of time… The Blu-ray format is an ideal 4K delivery platform as it is bound to evolve with larger capacity discs and faster transfer speeds – maybe we’ll get a better idea of Sony’s intentions when they reveal their Playstation 4. In the meantime it’s worth noting that HDMI V1.4 is already capable of handling 4K images and the newer MPEG-4 H.264 and JPEG 2000 compression technologies are more than up to the task too. In January 2012 Sony, LG, Panasonic and JVC all introduced 4K home display technologies at the CES (Consumer Electronics Show) in Las Vegas…

4K is here to stay whether we like it or not (we do!) – its high demands on bandwidth, storage and processing mean that at the moment it’s not for the faint-hearted, but the fact is that it’s not as technically complex as 3D so we shouldn’t be too afraid!